Showerhead Biofilms Can Host Pathogens

There are multiple areas in your home where bacteria find it easy to grow. Bacteria thrive in a warm, moist environments. One common household item that can harbor nearly 360 different species of bacteria is your kitchen sponge. However, while putting a sponge in the microwave for several minutes may kill some bacteria it doesn’t kill the worst ones.1

This is one reason Philip Tierno,2 professor of microbiology and pathology at New York University School of Medicine, says water temperatures need to be at least 140 degrees Fahrenheit (F) to kill bacteria and germs on your clothing (most automatic dishwashers are set at 120 F). The truth is bacteria are very resilient, even to heat.

Other common household items you may not have recently cleaned that are also prime environments for bacterial buildup are your trash can, computer keyboard, remote controls and cellphones.

Items handled frequently but cleaned infrequently are potential targets for bacterial growth. For instance, cellphones may have more total bacteria on the keys and screen than your toilet seat, kitchen counter and doorknobs combined.3

In a recent study, researchers found your showerhead is another household item likely growing more bacteria than you may imagine. Data analysis found regions in the U.S. where Mycobacteria were most prevalent in shower heads were the same areas where nontuberculous Mycobacteria (NTM) lung infections were most common.4

Nontuberculous Mycobacteria May Reside in Your Showerhead

Researchers from the University of Colorado surveyed 656 household showerheads from across the U.S. and Europe,5 finding they often harbor abundant Mycobacterial communities which differ depending upon the geographic location, water chemistry and water source.6

They also found U.S. water systems treated with chlorine disinfectants had a particularly high abundance of certain types of Mycobacteria not found in Europe where chlorine is not used.7 The results highlight public health concerns related to biofilm buildup in water systems and shower heads.8

The researchers found areas of the U.S. where showerheads had a particularly high number of potentially pathogenic communities of Mycobacteria overlapped with regions where NTM lung disease were most prevalent. These areas include New York City, Hawaii, southern California and Florida.9 They believe this further demonstrates distribution of showerhead biofilms are predictable.10

The results of the featured study support previous research showing biofilm growing on showerheads contained opportunistic pathogens, including NTM, leading the researchers to conclude showerheads present a significant potential exposure to aerosolized bacteria.11

Data also revealed plastic showerheads had a wider range of bacterial growth than metal heads.12 The study's lead author, research technician Matthew Gebert from the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, explained the results of the study and the importance for homeowners to routinely clean their showerheads:13

“Bacteria grow and persist in biofilms coating the inside of showerheads and shower hoses despite the seemingly inhospitable conditions found in these habitats.

These bacteria must tolerate rapid temperature fluctuations, long intervals of stagnation or desiccation followed by high-shear turbulent flow events, and the low nutrient and organic carbon concentrations typical of most drinking water.

In many cases, showerhead-associated bacteria must also be able to tolerate residue from the chemical disinfectants — including chlorinated compounds — which are often added to municipal drinking water to limit bacterial contamination.

Most of the bacteria that can become aerosolized and inhaled when the shower is in use are likely harmless. However, this is not always the case. Bacteria within the genus Mycobacterium are commonly detected in showerhead biofilms and throughout the water distribution system.”

What Are NTM Lung Infections?

NTM are found in the soil and water and affect humans and animals. When the bacterium gets into your lungs it can trigger a serious infection that may slowly scar and damage your lung tissue.14 In mild cases, you may not require treatment. However, more serious infections may require as much as two years of treatment to clear completely.

NTM lung disease is not tuberculosis, so you cannot pass it from one person to another. Instead, you get it from eating food or breathing air or mist containing the bacteria. The nontuberculous Mycobacteria get into your lung tissue, potentially triggering an infection and inflammation.

Most who swallow NTM don't get sick. You're more likely to get the disease after inhalation if you already have chronic obstructive lung disease, a weakened immune system, cystic fibrosis, a past infection with tuberculosis or any autoimmune disease, such as rheumatoid arthritis.15

You may be at a higher risk for NTM lung disease if you're a smoker, female, slender and white. The NTM germ lives in warm wet places, such as hot tubs, heated indoor pools and steamy bathrooms. Unfortunately, recurring infections or a relapse is not uncommon.16

Surgical resection may be necessary in selected cases with localized disease or when the infection is complicated by the formation of an abscess. According to the American Lung Association, there are over 80,000 people with NTM pulmonary disease in the U.S.17 Many of these are in older adults.

In some cases, the infections can become chronic, requiring ongoing treatment and have a significant impact on quality of life. The most common symptoms are cough that won't resolve, shortness of breath when active and coughing up blood (hemoptysis).18 Other symptoms include fatigue, low grade fever, night sweats and weight loss.

Disinfect Your Showerhead and Other Fixtures

While the research was completed on showerheads, it is likely prudent to also clean the other faucets in your home. In many cases removing the showerhead makes the process easier. However, in some cases this may not be possible, and it certainly is not easy to remove your bathroom and kitchen faucets for routine cleaning.

Showerheads may spray unevenly as they develop mineral deposits. This slows the flow of water and may increase the risk of bacterial buildup. You can remove these deposits on showerheads and in your faucets by soaking them with vinegar. In cases where the mineral deposits are particularly resistant, add baking soda to the soak.

If you're unable to remove the showerhead you can simply soak it by using a rubber band and plastic bag. Remember to use this only with a fixture made with chrome, stainless steel or another protected metal surface so the vinegar doesn't eat away at the surface.19

Slip the rubber band over the top of the shower head or faucet, looping it around the shower arm or faucet head once or twice so the bag stays in place. Fill a bag with white vinegar and attach it to the fixture slipping it underneath the rubber band. Allow it to soak for up to an hour before removing it, polishing the fixture and running clear water through it.

If the mineral deposits are still present, you may want to use a toothbrush to loosen the debris or a toothpick or safety pin to poke out additional deposits. Once the mineral deposits have been removed, disinfect your showerhead by soaking it in a diluted solution of colloidal silver and water. Use the same process with a bag and rubber bands if the fixture is unable to be removed.20

Silver has been used medicinally since ancient times and it's often referred to as the world's oldest antibiotic. In the Middle Ages wealthy people would eat with silver utensils to reduce the risk of illness, which is where eating utensils derive their name —silverware —despite being made from other metals today.21

Over the past years, several studies have shown silver is one of the most effective weapons in the battle against antibiotic-resistant superbugs.22,23 Silver interferes with bacteria's metabolism, increasing production of reactive oxygen species, products of normal metabolic processes in your body, which, in excess, can damage cell membranes and DNA.24

Add a Filter to Reduce Aerosolized Chlorine

Other substances can also be aerosolized from your showerhead. As I describe in this short video, chlorine, added to most municipal water supplies to reduce bacterial growth, is aerosolized during your shower. When chlorine interacts with organic material in the water supply or your body, it forms disinfection byproducts (DBPs).

These DBPs are far more dangerous to your health than chlorine and are, in fact, responsible for the vast majority of toxic effects from chlorinated water. Some of the most common DBPs forming from the reaction of chlorine and organic matter are trihalomethanes, classified as a Group 2B carcinogen.25

Although researchers once believed the majority of exposure to DBPs came from swallowing water, data now reveals this is not the only risk and may not be the most severe. On average you drink between 1 and 2 gallons of water per day, but expose yourself to 25 gallons when you shower.

Up to two-thirds of harmful chlorine exposure may be due to skin absorption and inhalation. Steam inhalation during a shower can contain up to 20 times the concentration of chlorine as tap water. The bottom line is chlorine and DBPs are another unseen danger in almost every shower.

You may minimize your exposure to aerosolized DBPs and bacteria by limiting the amount of time you spend in the shower or bath to 10 minutes or less and lowering the temperature of your water. Hot water opens the pores of your skin and allows a higher absorption rate of chlorine and other chemicals.

Additionally, steam contains high concentrations of vaporized gases and bacteria you can inhale. Using lower water pressure will decrease the amount of water and contaminants coming from the fixture. This is why I recommend if you can install only one filter, make it a shower filter.